The present invention relates to a programme retrieval system and method for retrieving a broadcast programme matching a desired programme, and a storage in which a programme retrieval program executable by a computer is stored.
It has been proposed to provide a video recording system wherein a determination whether or not an input image matches a desired programme to be recorded is formed and wherein video recording is performed for a predetermined period of time if a match is found between the input image and the desired programme, thereby enabling the video recording even if the start time of programme broadcasting is shifted in time (in Japanese Patent Laid-open (Kokai) No. Hei 10-285503, for example). In this video recording system, however, it is required for a user to specify in advance a broadcast channel since only one tuner is provided. Therefore, when a broadcast channel corresponding to the desired programme is unknown, it is not allowed to carry out reserved programme recording.
Furthermore, there is disclosed a video recording method wherein information on a broadcast programme to be transmitted immediately before the start thereof is checked against information pre-registered by a user through broadcast channel changeover on a time-division basis to retrieve a broadcast programme desired to be recorded by the user among programmes on a plurality of broadcast channels (in Japanese Patent Laid-open (Kokai) No. Hei 5-75555, for example).
According to the latter method mentioned above, under condition that the result of retrieval is successful, the desired programme may be recorded even if a broadcast channel corresponding thereto is unknown. However, in this method, since a retrieval time period is equal to a time length of pre-registered information, a comparison check is not made if transmission of the desired programme to be retrieved is started during a changeover to another broadcast channel. Resultantly, the result of retrieval is unsuccessful in most situations.
In view of the foregoing, it is an object of the present invention to provide a programme retrieval system and method wherein a desired broadcast programme can be retrieved without fail by setting up a proper relationship between a time length of pre-registered video/audio data and a retrieval time period per channel. It is another object of the present invention to provide a storage storing a programme retrieval computer program capable of retrieving a desired broadcast programme without fail in the manner mentioned above.
In accomplishing these objects of the present invention and according to one aspect thereof, a channel changeover is performed at a time interval which is less than a time value attained through division of a time length of a pre-registered key programme part, namely, a key for retrieval (hereinafter referred to as a retrieval key) by the number of retrieval object channels, and a determination is formed regarding whether or not a programme particle input at each time interval of changeover is found in the retrieval key. In this arrangement, since the time length of the retrieval key is longer than the sum of time intervals on all the channels, it is possible to prevent occurrence of unsuccessful retrieval.
In retrieval operation, programme particles are checked successively against a retrieval key in a time-shifted sequence from the beginning of the retrieval key. If a match is found anywhere in the retrieval key, it is determined that retrieval is to be made. A determination to be formed with respect to a time length of the retrieval key is completed before a changeover to the next channel.
In a situation where a retrieval object programme starts during the above-stated time interval so that a time length of the retrieval object programme becomes shorter than the above-stated time interval, a determination time may be shortened to cause incomplete retrieval. In this case, retrieval is ensured under condition that the retrieval object programme is continued to be applicable to the above-stated time interval when the channel concerned is selected again after a changeover cycle. That is, it is desirable to provide a time interval which is less than a time value attained through division of a time length of a retrieval key by xe2x80x9cthe number of channels + 1xe2x80x9d.
These and other objects, features and advantages of the present invention will become more apparent in view of the following detailed description of the preferred embodiments in conjunction with accompanying drawings.